1. Field of the Invention
Photoresists have been widely used in the lithographic production of integrated circuits such as IC and LSI, display devices such as LCD and EL devices, printed boards, micromachines, DNA chips, microplants, etc. The present invention basically relates to a cleaning composition for removing photoresists from various surfaces such as surfaces of substrate. The present invention further relates to a method of removing etching residues formed in the lithographic production and impurities remaining on the surface of substrate.
2. Description of the Prior Art
Alkaline cleaning compositions, such as a composition comprising an alkanol amine and an organic solvent and a composition comprising a quaternary ammonium hydroxide and an organic solvent, have been conventionally used to remove photoresists (U.S. Pat. Nos. 4,276,186, 4,770,713, 4,403,029 and 3,673,099). However, these compositions containing alkaline compounds to be used in the photoresist stripping process are generally less efficient for use in the recent production of semiconductor devices and liquid crystal display panels which requires fine processing and short-term treatment. Therefore, the need continues for more efficient compositions.
Unlike the removal of organic substances such as resists, the known compositions are less effective for removing resist residues, which are probably made of inorganic substances, such as sidewall polymers formed on substrates through a dry etching process and a subsequent ashing process. Alternatively, the known compositions are unfavorably corrosive to the materials on substrates.
To remove such drawbacks, compositions containing hydroxylamine have been proposed in Japanese Patent Application Laid-Open Nos. 4-289866, 6-266119 and 9-296200. Hydroxylamine is effective for removing resists, and also quite effective for removing resist residues formed by the ashing process after the etching process. However, hydroxylamine is easily decomposed. In addition, since hydroxylamine is available as aqueous solutions, the formulating latitude is narrow. Further, the proposed compositions cause corrosion, particularly, if materials containing titanium are used.
Japanese Patent Application Laid-Open Nos. 4-289866, 6-266119 and 9-296200 teach that hydroxylamine derivatives such as acyl-substituted and alkyl-substituted hydroxylamines are also effective. However, the inventor has experimentally found that the proposed derivatives are extremely poor in the capability of removing resist residues as compared with non-substituted hydroxylamine.